Cerebral Blood Flow During Anxiety Provocation

It has been suggested that traumatic reactions result from the failure to integrate the trauma withexisting cognitive schemata, whereas phobias represent biologically influenced adaptation patterns.This implies that central nervous system (CNS) organization of traumatic reactions may differ fromthat of phobic reactions. In this article, we review our previously published work on anxiety and regionalcerebral blood flow (rCBF). By using positron emission tomography and [15O]-butanol, relativerCBF was determined in 14 subjects with simple animal phobias exposed to visual phobogenicstimuli and in 6 bank officials exposed to a video showing an armed bank robbery that they recentlywitnessed. Subjective and physiologic indices of fear and anxiety were elevated by the activation conditionin both groups. Phobic stimulation elevated rCBF bilaterally in the secondary visual cortexcompared with neutral stimulation but reduced rCBF in the hippocampus and in the prefrontal,orbitofrontal, temporopolar, and posterior cingulate cortex. Compared with neutral stimulation, videoof a robbery increased rCBF bilaterally in the primary and secondary visual cortex, the posterior cingulate,and the left orbitofrontal cortex. Decreased rCBF was evident in Broca’s area, the left angulargyrus, the left operculum, and the secondary somatosensory cortex. Hence, visually induced fear andanxiety are associated with alterations in limbic, paralimbic, and cortical brain regions that are of relevancefor cognition and affect.